The present invention pertains to a rubber bearing with radial travel limitation and at least one damping agent channel, which comprises an inner part and a tubular inner contour, an elastomer, which is connected to the inner part and is connected thereto by vulcanization, and a channel carrier, which is formed from one or more plastic parts. In addition, a cage consisting of a casting or sheet metal is vulcanized into the elastomer.
Rubber bearings of various designs are frequently used especially in automobile manufacture. Depending on the intended use, greatly different requirements are imposed on the damping properties of the bearings. In some cases, the bearings are designed such that they make possible a hydraulic damping of forces introduced radially, due to the material properties of the elastomer, besides the damping. This is guaranteed by the elastomer being vulcanized with the inner part being surrounded by a ring-shaped element, which is made, in general, from plastic, and by chambers being formed between the parts for receiving a liquid damping agent and due to the shaping of the outer contour of the elastomer and of the inner contour of this element or of a sleeve pushed over the elastomer during the assembly. As is also known for other systems based on hydraulic damping, the damping is achieved by the displacement of the damping agent present in the chambers. It is necessary for this for the chamber to be connected by a channel, which makes it possible for the damping agent to move from one chamber into the other depending on the load on the bearing. Various procedures have become known for preparing the damping agent channels. One possibility is to prepare the damping agent channel in the elastomer. However, it is more advantageous and more customary to surround the elastomer with a plastic element, which forms stop surfaces for a travel limitation at the same time and is further used, in addition, as a channel carrier. The channel is formed by a groove recessed in the channel carrier, generally between the channel carrier and an outer sleeve of the bearing.
Such a bearing has been known from DE 36 17 787. In the solution described in this document, the elastomer is surrounded by a two-part element used as a channel carrier, wherein the channel is formed in the outer circumferential surface of the channel carrier. Another example is given in DE 197 29 290. The fact that the element arranged around the elastomer for the channel is designed as a two-part element in the above-mentioned solution (DE 36 17 787) is considered to be disadvantageous in this document. To make it possible to mount the element, it has an opening and does not surround the elastomer completely. It can be determined from the document that the internal diameter of this opening is greater than the diameter of the inner part connected to the elastomer. As a result, the length of the channel is shorter than in the solution according to DE 36 17 787, which may be disadvantageous especially with respect to a possibly desirable mass damping, which is brought about by the quenching effect caused by the mass of a damping liquid swinging to and from.
The object of the present invention is to provide a rubber bearing with radial travel limitation and a damping agent channel, in which the length of the damping agent channel provided by means of a channel carrier can be made variable to achieve different damping properties, while the channel carrier can be mounted easily at the same time.
According to the invention, the bearing has an inner tube, to which an elastomer is connected by vulcanization. The elastomer is surrounded by the channel carrier, which comprises one or more plastic parts and is supported on the elastomer by means of support elements. The damping agent channel integrated in the outer surface of the channel carrier connects the chambers for the damping agent, which are provided between the elastomer and the channel carrier. According to the present invention, the channel carrier has recesses in the area of the chambers for the discharge or the entry of damping agent, which, connected to one another by the damping agent channel, are arranged on the circumference of the channel carrier, in the area of the support elements and opposite these. At the same time, the channel carrier on its inner contour and/or the elastomer on its outer contour has a depression in the area of the stop surfaces for the radial travel limitation for enclosing damping agent during the coming into contact of the elastomer with the corresponding stop surface as a consequence of an inward deflection of the bearing brought about by a force introduced radially.
According to one embodiment of the present invention, a hole for allowing damping agent to escape is provided in the channel carrier in the area of the depressions formed in the stop surfaces. Due to the arrangement of the recesses and optionally of the holes, the circulation of the damping agent between the chambers, but also within a chamber is made possible. In addition, the holes in the depressions of the stop surfaces for the radial travel limitation make possible the circulation of the damping liquid enclosed there under the effect of a corresponding force.
In one embodiment of the present invention, the damping agent channel arranged in the outer surface of the channel carrier is extended beyond the recesses provided in the area of the chambers. As a result, damping due to the quenching effect of the mass of the liquid (so-called mass damping) is achieved, besides the viscous damping brought about by the circulation of the damping agent between the chambers. The holes in the depressions of the stop surfaces are arranged in this extension of the channel. The damping agent can also circulate within one chamber through such a hole and the recess in the channel carrier, which recess is adjacent to it and borders on the stop surface.
Another advantageous variant pertains to the provision of additional channels for the damping agent, which extend at right angles to the damping agent channel which connects the recesses and extends concentrically around the axis of the bearing, wherein the holes in the depressions of the radial stops are arranged in these additional channels. If the circular channel is additionally extended over the recesses in the channel carrier, corresponding to the embodiment explained above, the circular channels and the channels which cross them and extend in the axial direction intersect one another in one of the holes provided in the depressions of the axial stops.
According to another advantageous embodiment of the bearing according to the present invention, a lip, which acts as a valve for the damping agent moving in the damping agent channel, is made convexly or concavely in one piece with the elastomer in the area of the support elements. The mobility of the lip or the opening behavior of the valve and thus ultimately the damping behavior of the bearing are determined by the geometric design of the support elements.
As was emphasized above, the channel carrier may have a one-part or multi part design. A one-part design can also be considered to be advantageous in the sense of the present invention, in which the channel carrier surrounds the elastomer over an angle of about 300xc2x0. The recesses provided in the channel carrier opposite the support elements are designed as perforations in this case.
In another possible design, the channel carrier is made from two plastic parts, which are shaped such that they are fixed in their position due to their shape. However, it is also possible to bring about the fixation of two plastic parts forming the channel carrier by a pin.
In another possible design, the channel carrier comprises two plastic parts, which are connected to one another by means of a hinge. The bearing according to the present invention is characterized, especially concerning the design of the channel carrier, by the fact that the channel carrier can be mounted easily and the length of the channel can be easily varied corresponding to the required damping behavior, maintaining the basic shape of the channel carrier.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.